Antifoam compositions and uses thereof



Unite essi e-te ApplicationDecernber 1t), 1956 Serial No. 627,153

Claims; ((1252-321) No Drawing.

This invention, in general, relates to new and'improved antifoam compositions and to newand useful methods fbi' preventing, reducing or inhibiting foamingflin aqueous systems.

As is well known,foaming is a source of trouble in niimy industrial processes. One of the difficulties is'that the foam produced in suchpr'ocesses occupies space'which would normally be available for compositions being' proc essed and hence reduce the capacity of the app'aratus'in which the process is being practiced. For example, foam ing is a problem in the manufacture of wood pulp and pap s v There are two basic manufacturingprocesses involved in the-manufacture of paper. One is themanufacture of the pulp and the other is the formation of the pulp into paper or paperboard. Pulp manufacture may be divided into three main classifications: groundwood, chemical (kraft and sulfit'e) and semi-chemical (chemi-groundwood). In the refining of the pulp in any of the above classifications there are various stages such as screening,

washing, thickening and bleaching wherein undesirable foaming may occur. Thepoints at which" antifoam compositions are added will vary depending upon the particular foaming problem. The antifoam usually is added just prior to the point where foarn'control is.desired. This may beto the screens, deckers, water showers, pumps, regulating head boxes, etc.

Thereare two basic methods for the manufacture of paper and paperboard. The paper sheet may be formed on a cylinder machine or a Fourdrinier machine. Foam ing can occur at various stages during the paper manufacturing process, and, again depending on the particular foam problem involved, the antifoam composition is added to the feed or screen pump, screens, headboxes or showers of the cylinder machine or to the headbox, fan pump, showers or wire pit of the Fourdrinier machine.

One of the objects of the present invention is ,to provide new and improved compositions for preventing, reducing or inhibiting foam formation in aqueous systems. Another object of the invention is to provide. methods of using said compositions in preventing, reducing or inhibitingfoam formation in aqueous systems.

Other objects will appear hereinafter. y In accordance with the invention, new and improved antifoam compositions are prepared. in a water base rather than the usual oil base. The water base lends to the ease of dispersibilityof the antifoam in an aqueous, f aInable liquid. The active antifoaming agents are long chain fatty acid esters of polyhydric alcohols, lecithin, and free fatty acids above C preferably stearic acid. The antifoaming ingredients are dispersed in an aqueous base carrier while utilizing a small amount of a. liquid hydrocarbon and/or lower molecular weight alcohol of one to five carbons. In one embodiment of the invention, the solventsare not present to any considerable degree-the formulation being in the form ofa paste.

A small'amount of alkali, e.g., sodium, potassium, or

ammonium hydroxide, is addedto form a soap with fatty acid. This soap, in a quantity at least about 86% by weight of the formulation, acts as a solubilizer for the organic constituents in the formulation.- Sufficient alkali may be added to neutralize allof the fatty acid, but, preferably, there is some free fatty acid in the formulation.

The fatty acid esters of polyhydric alcohols may be compounds such as propylene glycol monostearate, polyethylene glycol monostearate and sorbitan monooleate. Others include compositions such as glyceryl monoand distearates, dipropylene and diethylene glycol monostear ate, triand tetrapropylene and ethylene glycol monostearates, ethylene glycol monostearate, and preferably monostearates and distearates of polyethylene glycols of an average molecular weight of at least about 200, and sorbitan monostearate.

The function of the fatty acid is twofold(1) solubilization of the organic constituents in the liquid medium by formation of a soap of the fatty acid and (2) optimum antifoam activity. For the solubilization function, any

fatty acid can be used. The saturated acids, preferably having 18-22 carbons, are preferred to obtain optimum antifoam activity} Examples of these'saturated acids are lauric, myristic, palmitic, stearic, hydroxy stearic, arachidic and behenic acids, or mixtures of saturated acids, preferably predominating in 18-22 carbon acids, such as hy-, drogenated tallow fatty acids and hydrogenated marine fatty acids.

The antifoaming compositions of this invention fall within the following general range:

Composition Pa ts by Wei rht Fatty acid 3-11 Lecithin 1030 Fatty acid esters of polyhydric alcohols 0-9 Where a liquid formulation is desired, liquid hydrocarbons and/or lower molecular weight alcohols, and

water are employed in sufiicientquantities to efiect a liquid, preferably clear formulation. The choice of a particular lower aliphatic monohydric alcohol as the organic solvent, used either alone, in admixture with other lower aliphatic monohydric alcohols, or in combination with an aliphatic hydrocarbon solvent or' solvents, which may range from the lower boiling point naphthas to the higher boiling white oils, is'largely a matter of attaining maximum solubility at the lowest formulation cost. Of the lower aliphatic monohydric alcohols, isopropanol is preferred as it provides the maximum solubility at the lowest cost. 1

was tested for its antifoam action on a sample of kraft paper stock. In the-test procedure, 200 milliliters of screened (#12 sieve)v stock is'placed in a 4.6 x 50 centimeter glass tube. It is then shaken both after the addition of 0.2 milliliter of 1% sodium rosin solution (made up in tap water diluted, 1 :1 with deionized water) and of varying antifoam dosages. The mixture in the glass p.p.m. dosage] Foam Height at 60 Seconds, cm.

Foam Height at 30 Seconds, cm.

Table II p.p.m. dosage] Foam Height at 30 Seconds,

Foam Height at 60 Seconds, cm.

Foam heights on control samples (no antifoam) are approximately 45 cm. of foam in 30 seconds.

The stock used in the foregoing test was prepared by shredding 18 grams of kraft pulp, torn in several pieces, for fifteen minutes in a Hydrapulper containing 860 grams of water. One hundred forty grams of black liquor, obtained from a paper manufacturing company, is then added to the pulp and the mixture is allowed to stand overnight. It was then filtered through a #12 sieve, pressed to a wet-weight of 76 grams, and diluted to one gallon with water of a desired hardness.

In similar tests with another foaming kraft stock, a foam height at 15 p.p.m.'dosage was 2.4 at 30 seconds and 2.8 at 60 seconds.

The antifoam compositions of this invention are particularly useful in controlling foam in pulp and paper manufacture, particularly the kraft process, where the familiar oil base antifoams are relatively ineffective. The antifoams of this invention control foaming at virtually any temperature and under pH conditions as low as 2 or as high as 12. It is preferable to add the defoaming composition to the material being treated at a point at close as possible to the source of the foam. In the paper making operation, for instance, most of the foaming difiiculties occur on the screen boxes and the cylinders (of a cylinder paper making machine). The defoaming compositions of the present invention may be added at any convenient point such as heretofore described. The compositions introduce no contamination to the paper pro duced and, being a liquid, are easily and accurately proportioned into the foaming media. The antifoam compositions are rapidly dispersed in aqueous systems and produce fast foam elimination. For pulp or paper mill applications the dosage usually varies between $4 and 2 pounds per ton of dry fiber. In other processes the dosage will vary depending upon the severity of foaming conditions.

Field trials with the antifoam composition of this invention are indicative of the success thereof in controlling peeqarmecesso-oe foam in pulp and paper manufacture, notably where oil base antifoam formulations have failed to satisfactorily control the foam. In the manufacture of newsprint consisting of 12% sulfite, 35% chemi-groundwood and 53% groundwood fibers, a test was made with an antifoam formulation corresponding to that of Example I. The particular mill had its own chemi-groundwood and groundwood pulp mills. The chemi-groundwood process is a partial chemical cooking prior to grinding the logs for pulp. The chemi-groundwood pulp tends to foam considerably more than the straight groundwood pulp. The principal difliculty in the chemi pulp mill arising from the foam is the air binding of the stock pumps following coarse screening. The commercial antifoam in current use at the mill handled the foam at the coarse screens and pumps. There was, however, a good deal of foam in the fine screens and deckers.

The major part of the antifoam tests with the composition of this invention was made by feeding the aqueous base antifoam in the fine screening efiluent leading to the deckers. Oil base antifoam formulations showed practically no effect in controlling foam in the deckers. In contrast to the performance of the oil formulations, the aqueous base antifoam composition of this invention was highly effective in foam control. It was, particularly, noted that small slugs of one or two ounces of the antifoam composition almost immediately dropped the first decker level 3 to 4 feet by eliminating foam and entrained In the paper mill of the same company the aforesaid antifoam composition was fed at the fan pump into the headbox of a Fourdrinier machine at a rate of one to two pounds per ton of paper produced. The antifoam was effective in controlling surface foam in the headbox. Later, the antifoam'composition was fed to the showers of the headbox at the same rate of feed. During the course of a short run the headbox level dropped 3 to 4 inches. Competitive antifoams which were tried on this machine did not give satisfactory performance at economi' cal dosages.

In a pulp mill and paper mill of another company the most serious foam problem in the pulp mill was in the deckering of their sulfite pulp. The foam problem varied in intensity, depending upon the hardwood being processed. A moderate amount of foam was visible in the deck-er. A test was made with an oil based antifoam, the results of which were negative. The antifoam com position of Example I. was then tested. The foam disappeared from the decker and the decker level fell. Excellent foam control was obtained at a rate of 1.2 pounds of antifoam composition per ton of pulp. Competitive defoamers which were tested at the decker were ineffective.

The fatty acid esters of polyhydric alcohols heretofore described are polar in naturehaving hydrophilic and hydrophobic portions of the molecule. The hydrophobic portion of the molecule is provided by the aliphatic chain of C -C fatty acids and the hydrophilic portion of the molecule is provided by the hydroxyl group in the case of partial esters of polyhydric alcohols or by the oxyethylene groups, and in some instances by both hydroxyl groups and oxyethylene groups. In the case of the distearates of polyethylene glycols, for example, the oxyethylene portion of the molecule is sufficiently long to provide the desired hydrophilic properties. In general, a polyethylene glycol of a molecular weight of at least about 200 is sufiicient to impart the desired hydrophilic properties. The upper limits with regard to the molecular weight of the polyethylene glycol is largely determined by the particular solubility characteristics of the particular fatty acid ester with the particular solvent or solvents used in formulating the antifoam. In general,

the molecular weight does not exceed 1500, and for speeific esters may be considerably less than 1500.

The term alkali soap is intended to mean the alkali metal, particularly sodium and potassium, and the ammonium soaps of fatty acids.

The invention is hereby claimed as follows:

1. Antifoam composition consisting essentially of in parts by weight:

Parts Fatty acids of more than 11 carbons 3-11 Lecithin I 10-30 Polar esters of polyhydric alcohols and long chain fatty acids -9 at least a portion of the fatty acids being in the form of an alkali soap to provide an amount of soap equal to at least 84% by weight of the antifoam composition.

2. Liquid antifoam composition consisting essentially of in parts by weight:

Parts Fatty acids of more than 11 carbons 3-11 Lecithin -30 Polar esters of polyhydric alcohols and long chain fatty acids 0-9 Parts Saturated fatty acids of more than 11 carbons 3-11 Lecithin 10-30 Polar esters of polyhydric alcohols and long chain fatty acids 0-9 at least a portion of the fatty acids being in the form of an alkali soap to provide an amount of soap equal to at least by weight of the antifoam composition.

4. Liquid antifoam composition consisting essentially of in parts by weight:

Parts Saturated fatty acids of more than 11 carbons 3-11 Lecithin 10-30 Polar esters of polyhydric alcohols and long chain fatty acids 0-9 Parts Saturated fatty acids of more than 11 carbons 3-11 Lecithin 10-30 Fatty acid partial esters of polyhydric alcohols 0-9 at least a portion of the fatty acids being in the form of an alkali soap to provide an amount of soap equal to at least by weight of the antifoam composition.

*6. Liquid antifoam composition consisting essentially of in parts by weight:

Parts Saturated fatty acids of more than 11 carbons 3-11 Lecithin 10-30 Fatty acid partial esters of polyhydric alcohols 0-9 at least a portion of the fatty acids being in the form of an alkali soap to provide an amount of soap equal to at least by weight of the antifoam composition; and a suflicient amount of a lower monohydric alcohol and water to effect a solution of the organic constituents in said alcohol and water.

7. Antifoam composition consisting essentially of in parts by weight:

Parts Stcaric acid 3-11 Lecithin 10-30 Polar esters of polyhydric alcohols and long chain fatty acids 0-9 at least a portion of the stearic acid being in the form of an alkali soap to provide an amount of soap equal to at least 8 4% by weight of the antifoam composition.

8. Liquid antifoam composition consisting essentially of in parts by weight:

Parts Stearic acid 3-11 Lecithin 10-30 Polar esters of polyhydric alcohols and long chain fatty acids 0-9 at least a portion of the stearic acid being in the form of an alkali soap to provide an amount of soap equal to at least 54% by weight of the antifoam composition; and a sufiicient amount of a lower monohydric alcohol and water to effect a solution of the organic constituents in said alcohol and water.

9. A process for suppressing formation of foam in a foamable aqueous medium which comprises adding the composition of claim 1 to the aqueous medium in an amount sufiicient to control said foam.

10. A process for suppressing the formation of foam in water pulped with cellulosic fibers which comprises adding the composition of claim 1 to said pulped mass in an amount between about A and 2 pounds per ton of pulp.

References Cited in the file of this patent UNITED STATES PATENTS 2,645,617 Mayhew et a1. July 14, 1953 2,715,614 Snook Aug. 16, 1955 2,727,009 Jursich Dec. 13, 1955 

1. ANTIFOAM COMPOSITION CONSISTING ESSENTIALLY OF IN PARTS BY WEIGHT: 